Governor with two-position low idle stop



April 16, 1968 R. H. MILLER 3,377,870 v GOVERNOR WITH Two-POSITION Low IDLE s'TQP Filed July 16, 1965 llll ` lWVENTR. ROBERT H. MILLER vBY ATTQQNE'YS United States Patent Olice 3,377,870 GOVERNOR WITH TWO-POSITION LOW IDLE STOP Y Robert H. Miller, Peoria, Ill., assignor to Caterpillar Tractor Co., Peoria, Ill., a corporation of California Filed July 16, 1965, Ser. No. 472,487 1 Claim. (Cl. 73-543) ABSTRACT OF THE DISCLOSURE A flyweight governor of the kind commonly used on internal combustion engines which has a low idle stop mechanism and also a second stop mechanism which is effective at a speed slightly greater than low idle.

Governors are usually designed to be set for any desired engine speed by a hand lever or foot pedal. In order to prevent an operator from accidentally shutting the engine down when it is intended to adjust the governor to a position for very slow speed or low idle, a resilient stop mechanism is customarily employed. This mechanism, known as a low idle stop, creates a slight resistance that is felt by the operator signaling the fact that the governor is in low idle position. Additional force may be employed to overcome the resilient stop mechanism when it is desired to shut the engine down.

There are instances where it is desirable to reduce engine speed to a point higher than low idle. For example in trucks or other vehicles employing an electric drive powered by an internal combustion engine, the operator customarily reduces engine speed on a long down grade. If the engine is reduced to low idle subsequent return to higher speed is impaired in overcoming the resistance of the generator and a lag in acceleration is experienced which causes slowing down of the vehicle.

It is the object of this invention to provide an improved low idle stop mechanism for governors and particularly to provide means for signaling an operator that a governor position has been attained, that is low but somewhat greater than low idle.

Further and more specific objects and advantages of the invention and the manner in which it is carried into practice are made apparent in the following specification where reference is made to the accompanying drawing.

In the drawing:

FIG. 1 is a sectional view through a well known type of governor to which an auxiliary low idle stop embodying the present invention has been applied; and

FIG. 2 is an enlarged fragmentary sectional view taken on the planes represented by the line II--II of FIG. l.

The governor in connection with which the present invention is illustrated is of a known type fully described in the United States patent to John H. Parks No. 2,961,229. It comprises the main governor spring adapted to be compressed by the spreading action of yweights 12 driven by a gear train 14 at a speed comparable to engine speed. The ilyweights engage a thrust plate 16 which is Xed to a fuel control member or rack bar 18 slidable through one of the gears in the train 14 and adapted to adjust fuel pumps (not shown) in a well known manner. Movement of the bar to th left under the influence of the spreading yweights tends to reduce the supply of fuel to the engine. Lever means comprising a pair of lever elements 20 and 22, see also FIG. 2, fixed to a common shaft 24 are engageable with a spring seat 26 to increase the tension of the governor spring 10 when the levers are rocked in a clockwise direction. Manual or pedal actuated means are connected with the shaft Z4 by suitable linkage (not shown) to impart rocking motion to the shaft and lever means.

The governor is provided with a low idle stop mechanism described in the above mentioned patent to Parks which comprises a rod 28 threaded through a boss 30 in the governor housing so that it may be longitudinally adjusted by turning a hexagon head on the Vrod shown at 32, an enlargement 34 on the rod and a spring biased detent 36 (see FIG. 2) coact to provide a conventional low idle stop. The detent 36 is mounted between the two arms 20 and 22 of the speed control lever and moves in an arcuate path represented by the broken line 38 in FIG. 1 as the lever is swung between high speed and shut down positions.

In FIG. 2 of the drawing, the uppermost dotted line position represents the position of the detent 36 when the engine is shut down. The next dotted line position is that assumed by the detent during low idle and the full line position shows the detent at a higher low idle position provided for :by the present invention. In this position, it is resting against a second stop member 40 which embraces the rod 28. The stop 40 is -u-rged against the lower inclined surface of the stop member 34 by a light spring surrounding the rod as shown at 42. The rod is tapered inwardly adjacent the stop 34 and the inner surface of the stop 40 is tapered outwardly to produce a loose fit which enables the stop 40 to be moved inwardly and downwardly against the force of spring 42. Thus while the stop 40 cooperates with the detent 36 to signal the operator that a high low idle position has been attained, it is very much mo-re easily overcome than the stop 34 because the spring 42 is very light in comparison to the detent spring.

With the construction described, a vehicle may be retarded on a low down grade by slowing the engine to the point where the detent rests against the stop 40. Engine speed can then be recovered by advancing the lever 20-22 in a clockwise direction without undesirable lag caused by inertia of the load imposed by the generator being driven in an electric drive type of vehicle.

I claim:

1. In an engine governor of the spring biased centrifugal yweight type which includes adjustable means to vary the effective lforce of the spring and resilient stop means engageable by the adjustable means to signal the presence of the adjustable means at a low idle position, the improvement which comprises a second resilient stop to signal the presence of the adjustable means at a position representing engine speed slightly faster than low idle, the force required to pass the resilient stop means :being greater for the first than for the second stop means, said adjustable means including a lever and a spring biased detent carried by the leve-r, said lirst stop comprising a rod having an enlarged portion engageable by the detent, and said second stop comprising a member surrounding the rod and resiliently biased toward the lirst stop, said member also having an enlarged portion on its outer diameter, and said rod having a reduced diameter within said member to permit deection of the member when it is engaged by the detent.

References Cited UNITED STATES PATENTS 2,961,229 11/1960 Parks 73-513 3,276,439 10/ 1966 Reichenbach 123-140 XR JAMES I. GILL, Primary Examiner.

Patented Apr. 16, 1968. 

